The truth is that it simply does not matter in the slightest what resource you use.
99.9% of your results will depend on your consistent focused effort.
.1% will depend on the source material.
So choose whichever one is easiest on your eyes and wrist.
Personally, I used chessimo about 10 minutes every single day for about 1.5 or 2 years.
So whats the best way for me to train my tactics. I am willing to spend money, but only if it is WORTH it. I know there are free tactics trainers out there as well.
Some things I have looked at.
Chessimo
CT 4.0 at okchess.com
chesstempo.com (free website)
chess.emrald.net (free website)
and ofcourse chess.com membership, but since this is monthly it adds up
So any advice is appreciated. I have lazlo polgar's chess tactics book, which i work through but i like working on the computer more.