I did end up purchasing an Ontario RAT-1 however, plain edge (not a tanto either) and fell in love with it more. If I didn't I would have kept the SOG.
Some of the "beefiest" tantos I've seen have been Striders and the Chris Reeve Ummnamazan (Umnamza.....Ummnnnammmazanana....you know....the big one)
Kershaw makes some tantos, my carry knife about 6 years ago was a Kershaw 1550T before they discontinued it, good knife but the tips were thin and broke the tanto tip and bent the clip point tip (1550 after I lost the 1550T)
Benchmade makes overall good knives too and they offer tantos Products
In case you missed it with your options that you have listed. tanto, assisted open, under 100 bucks, (and some you didn't mention) super tough, solid steel, awesome company, great warranty, made in the USA!! with all those cryteria being met the kershaw blur tanto is the knife for you!
If you want to keep you 100 dollar budget and get rid of the tanto requirement then I would recommend you the Zero Tolerance 0350. all the positives of the blur but a bigger beefier blade. it might run you 120 but you can find them used for around 90-100 bucks.
Be forewarned though. knives are very addicting also, just like guns and all the other toys we love
If you really want a nice assisted opening folder go with a Kershaw, great quality! If you want a fixed blade I'd recommend the smaller Ka-Bar TDI's. They fit wonderfully on a belt.