Dolphin is a fine basic fin that will get you started on a reasonable budget. I'm about your size and I used to have a medium stiffness fin. It was great for dynamic, but for CW I would've perhaps liked a bit harder one. Decide which is more important to you, CW or DYN. Generally speaking, people seem to prefer a softer blade for DYN and harder for CW. If you are strong and muscular, a harder blade MAY be in order, but again, it's a matter of personal preference. I once tried an ex-hard dolphin and it felt like it's not even bending, just going up and down (=not good). But I've seen the owner do over 125m dyn on it, so it can't be all bad. If you can't try one before you buy, then I'd say medium or hard are the safest bets.
In my opinnion, a blade that is too soft is better that one that is too hard. With a harder blade, it's easier to learn the wrong technique and you'll be bending you knees and kicking with your legs. The kick shoud come from your upper body (back, abdominals etc), the legs are just delivering that kick to the fin...Leg's are only a hindurance for a monofin swimmer. I believe a dolphins fin is more or less attached to it's back. Thus the much better efficiency in water. But don't go sawing them off just yet
But that's why for a beginner I would recommend rather a softer that hard. You can always buy a new monofin, but re-learning a wrongly developed technique can be a pain in the ass...
The special fins dolphin is the most common monofin I see, but that's propably due to their close proximity to us and excellent service. I'm sure other brands have good, basic fins as well, but I couldn't tell you about those.
Currently I have a russian made "wing" mono. I have no idea of the brand, the only marking I can find is "spine" on the foot pocket. I bought it used from another freediver. I hear they sell at about 150 or so, I'm not sure. I really like it, but I couldn't even guess where you could obtain one.