What type of wetsuit is best?

Honestly, the more wetsuit you have, the more advantage. Long leg, long sleeve.

Sleeveless can work if you have serious issues with shoulder mobility, but a good quality suit should have a flexible enough shoulder.

The best wetsuit is going to be the one that fits, to be honest. Materials made aren't that different.

Go to your local tri shop, ask questions, try a bunch on.

If you have to go online, Xterra has a great return policy for sizing, I went with their Vector Pro and have been pretty happy.

It isn't really a matter of what wetsuit is the "best" its more of what feels most comfortable on you and fits you the best. Everyone is different, so ones person recommendation of the best wetsuit could be the worse one for you.

I bought a blue 77 for a decent price under 200$ and have had good experience with it. Full length wetsuit, my only issues is my triceps swell up when swimming and I just have to pump water into my arms and its all better.

I think both can be useful depending on conditions. The full suit is useful when the water is cold and you clearly need a wetsuit. It will give you the biggest speed/buoyancy advantage although this is a bit less with stronger swimmers. Some people prefer sleeveless if they are uncomfortable with the restriction on the shoulders or have a fit issue due to a bigger upper body. To me those suits feel a lot less warm--maybe best for strong swimmers who have some natural "insulation".

I also have a sleeveless shorty sui that I use for sprint or Olympic distance races when water temps are borderline (barely wetsuit-legal--basically above 72 or 73). This happens to describe a lot of summer races in the Pacific Northwest. I also use it for open water training in those conditions and sometimes even cold pools. It gives less buoyancy advantage than a full suit but still some, and is a LOT quicker to get off than a full suit. I have a TYR Category 1 full suit and can't really recommend it. It's warm and buoyant, but I find its bit restrictive (maybe a fit issue) and haven't been impressed with its durability. I have been very happy with my ProMotion sleeveless shorty, though. I train in it a lot, including in our currently ice-cold school pool, so it's starting to fall apart, but it's held up much better to harsher, much more extensive wear than the other suit and I will happily replace it when it bites the dust.

It depends a bit on where you are… If you're in the NorthEast, especially if you race in the ocean, you want a long sleeve to stay warm. If you're in FL, then you may want a sleeveless (or you may not even need a wetsuit at all!) to reduce your temperature a bit.

Sleeveless allows for greater shoulder flexibility, making it a bit easier to swim. A full wetsuit will give you the best buoyancy.