The best jtag is the jasper jtag. Has great boot times and barely gets rrod. The best rgh is the trinity. I would get a trinity rgh because the slim is he newer console

It really all depends on how you treat your console. People have broken Jaspers, so you can't say "it never gets RROD" because that's a lie. I've had a Xenon for 2 years, and my friend has had his since early TU6. It's all on how you take care of your console. Some people reball their consoles. That will ensure that you have a solid GPU/CPU and not having any RROD issues for a long time(if done correctly). In my opinion, I love xenons, they take Type 1 and Type 2 KVs, not that it matters anymore but I enjoy the variety. My slim has had more issues than my xenon. But my xenon is reballed.

For the money, if you have a wallet full, then shoot for a Jasper. Not many people have Jasper jtags for sale, but if you can find one, it's not going to be cheap. Falcons, they are relatively easy to find. RGH1 falcons are fine, they have beautiful boot times. If you wanna go with cheap, you can probably spend $150 for a xenon jtag, the extra $50 would be to send it in to be reballed.

Look over your options. Choose what's best for you. Everyone is going to give you a bias opinion.