They are kinda two different animals.
First off the T-70 is a hardened hard core military spec instrument that is shock proof, water proof to 30' deep, and vibration proof, battery pack is hardened for CR 123s or AAs, comes with video cord, has remote control switch, is a clip on and a standalone, contains 5.56mm and 7.62mm BDC reticules, is resistant to .50 cal BMG recoil, is super hard core and is expensive. You can clip it on in front of any 4X scope and use it right away, will handle up to 6X day optic max but that cuts off the visible screen icons from view above 4X.
That said, it also has the AWESOME 0.5X, 1.0X unity, and 2.0X digital zoom, the 0.5X to me is absolutely required as we are hunting dangerous game in thick overgrown areas and that WFOV is to die for.
As far as visual, the LS64-35 is about and 8 out of 10 comaprison to the T-70, they have different firmware and software, although the new coming releases of RS64-35mm software and firmware could bring that up to 9 out of 10 real soon.
RS64-35m is a standalone only, half the price, internal battery works excellent and mostly forget about charging it up for an entire night while the T-70 will use batteries, especially if video recording. RS-64 is super easy to use, auto NUCs, saves presets for different rifles, basically is an all aroung Go-To thermal instantly ready for action.
Having both on different rifes, I use them for different purposes depending on where we are going and what the plan is, also the clip-ons are easy to loan out as just clip them on and start hunting.
The very best is the T-70, second best is the RS64-35mm, they both are worth every cent I paid for them and get used almost every night of the week one way or another.
I cannot choose for you and what type of hunting you do, they both have the same range and both will kill everything inside that range without a problem, just different ways of doing the same thing.
Being a hardened military operational thermal scope, the T-70 fits the bill for hardcore use toting around on ATVs/UTVs, swamps, etc., the RS64-35 takes allot of abuse too and never had any hassle with anything from either of them.
Oh, and did I say the 0.5X view is to die for, no other thermal scope has that???