Innerlining or open cell?

Depends how thick suit you take ? If 5mm take open cell.
If thinner, take with inner lining, because its more durable and easier to put on

Go open cell buy off the rack unless sizes do not work for you. Wash with water after use hang dry. All suits will wear out with use however the water your diving in is not that cold, so perhaps a perfect suit is not critical. Lots of folks will chime in on the importance of custum suit and this can be important for credability and status Marea also makes attractive expensive suit. I saw guy dive recent no packing dive to 74 meters in plastic fins and a off the rack suit. I like freediving not expensive diving good luck with your diving and equipment.

you could also get a 5mm opencell top and 3mm lined pants.

i think off the rack makes only sense if you have the detailed measures of each size, which are the base of the cut. haven´t found this on the elios site yet. -learnt this with my first order:
sent my detail measures and asked for advice concerning off the rack/tailormade. got answer that suggested off the rack. after receiving the suits i knew that for me only made to measure makes sense for elios orders. have done some made to measure orders since then - all perfect with very few water entering

also for me an inner lining is part of a inside out suit which is really a nice option. you can wear smooth in for peeing in every day. in case you wan´t some extra glide or for some reason you don´t want be wet before entering the suit you have a "nylon in" option

an open cell (with smooth out) has in my book no downside in the categories you asked for (after practicing a little how to get in). it will last not as long especially when worn in the sun - and before you throw it finally away it gets annoyingly delicate. ...not to speak of the water entering through little holes. if you dive not very often i´d always suggest open cell/smooth

Open cell is more comfy But also more fragile
With open cell, u need to use soap or something to put suit on

20/25 c is quit a range to cover. In 20c water, doing training for hours, when below it's colder (16, 12, 8c) then a 5mm open cell (medium density) inside, nylon outside is nice for my skinny tall body.
When I'm doing competition I obviously want less suit, and since I skip in water preparation, I have only 3mm. Now if the water is constant 20 all the way down, I would choose to have 3mm + vest. Now if you want comfort, more then super low drag performance, I suggest coated cell inside (easier then open cell), super stretch nylon outside, medium density neoprene. Ask for a low forehead cap (to keep the sinuses warm), and maybe an extra 3mm vest (same material).

The nylon outside makes the suit endlessly more durable, in trade for some flexibility. Something that good lubrication medicates. Smooth in and out is indeed more comfortable, faster and a bit warmer on the surface, but it will rip open very easy and spoil your day.

Also you can lend it to a friend knowing he will not break it instantly ..

Oh and there is also the sandwich option, smooth in, smooth out with nylon in between.
I have such a suit, from 2000... and it's very durable, but it is less flexible then single lining 5mm (mine was 4,5mm - 1,5mm more then the 3mm). So it is size critical. I think I may ask for a sample of the latest fabrics since I think the sandwich may have been improved with Higher stretch nylon than my OLD Beauchat Apnea 2000 suit had. Actually I think it's a really nice option in colder and windy climates, where you want smoothskin, warmth and durability.

Yeah choosing is difficult. If it's your first suit and only one, I would go for something durable, warm and comfortable. Good stuff for endless hours of recreational diving, learning the ropes without the fear of damaging your investment.

In Sweden in 19c water I was happy with my old standard 5mm (open Cell in, nylon out) for 1,5 hours without shivering. A 3mm would have me shiver within 5 to 10 minutes, if I skip food in preparation of a competition dive.
Being a bit on the warmer side helps to save energy.
In Egypt I dove in 26,5c water with just the 3mm upper piece (Nylon in, smooth out). The full 3mm suit was too warm.

It's funny that just 1c difference is easily noticeable in water compared to 1c change in air temperature.

I hope this is helpful.

Kars

"Ask for a low forehead cap", laag voorhoofd muts, means the cap will cover your forehead to just above your eyebrows. Normally it leaves your forehead exposed, not nice if you dive in cold waters and or have sensitive sinuses, it causes them to block. If you got long hair you may want to consult Elios to have an extra low forecap, because the big hair will pull it up, exposing your forehead once again.

In the Netherlands and Belgium 5mm is nice for long season diving, note I did not say all season. So here in the local lake 5mm is for me comfortable, especially when I hit the termoclines.

5mm full suit for Dahab maybe much, 5-3 is better, but just ask some locals about that.

Kars said:

"Ask for a low forehead cap", laag voorhoofd muts, means the cap will cover your forehead to just above your eyebrows. Normally it leaves your forehead exposed, not nice if you dive in cold waters and or have sensitive sinuses, it causes them to block.

Click to expand...

Many Ama divers in Japan wear hoods that are perfect for keeping the forehead totally warm. I'm planning on making one of these myself.

It is made of smoothskin neoprene and has 2 openings, 1 cut out just around the eyes and nose, so that the mask skirt seals around the smoothskin of the hood, not the diver's face, keeping water comletely off the forehead and temple areas.

There is a second hole for the mouth.

I've attached some photos that illustrate the style:

I have this, and its very good for cold water diving
I used it for 0...+3°C water.
Imersion; 2mm, nylon inside, smoothskin outside.