I preferred Turrican 2 over no.1 as well, although my opinion on both isnt drastically different. Turrican2, to me, just seemed like a fine tuned version of no.1.
For the record, the 1st level on both is a bit bland, but the secret/hidden stuff in no.2 gives it an edge. I also liked the spaceship scrolling shooter levels in no.2. more than the top to bottom scrolling leels in no.1.
No.3 also had its pros vs. the 1st 2, (technically more impressive at times), but in terms of raw gameplay didnt quite stack up.
Now, as for Thunderblade, opinions seem to vary pretty heavily. Personally I liked it, especialy at the time of release. To this day I prefer it to the megadrive version, but neither have aged well.