So I'm about to breakdown and buy my first wetsuit, most likely a shorty... Not a lot available close by so thinking of just ordering on-line, however I'm wondering about what size since I wouldn't be able to try it on first.

I'm 6'3" and about 210lbs. From the sizing charts that puts me almost perfectly between a L and an XL. Recommended size chart for L appears like it would be tight and the XL would be looser with room to breathe. So which is better? Snug or a little loose? Also wondering about thickness - I've seen mostly 2mm, 3mm and 4mm. Never had one before so any suggestions would be appreciated.