Hey guys, looking for opinions on which one to buy. Getting back into rc after a 10 year break, man has so much changed

Whichever one feels better in your hand. You're asking whether to get a Ferrari or a Lamborghini...

The M12S has an (arguably) imperceptibly faster response time. Also, I don't recall the Futaba offering a *antenaless receiver (i.e. 482), which is a plus for the Sanwa. On the flip side, the M12S is starting to feel dated with the LCD screen (seriously, my TV remote has a color multi-function screen) and the menu navigation is not the most intuitive. Additionally, as I recall, you cannot program all of the PGS servo functions without an external programming box. I believe you can access all of the S-BUS functions from the 7PX.

The Futaba design/amenities/feature set are a smorgasbord of 'latest and greatest', however most people in the racing crowd will site the slower response time.

Hard to say you would go 'wrong' with either one. Agree with the previous poster from the perspective of going with what is more comfortable.

I got tired of waiting for the 7PX and got the M12S. It is a fabulous radio and the response time is for real. I don't look at the screen when racing.

A Sanwa m13 should be out soon, right? It’s an arms race

Sanwa is only faster when using Sanwa servo's in their superspeed mode, otherwise Sanwa and Futaba are almost the same in performance. And beside that, I do not think a 2ms difference can be noticed.
Also Futaba has antenna less receivers and the receivers from Futaba are much cheaper than Sanwa. Regarding the programming of certain model servo's and ESC's it is done throug a port on the transmitter. The SBUS is just a different (network like) connection to connect servo's and telemetry sensors.

And to me, I do not care if a display is outdated, if the transmitter with its speed and functions is from this time it is good.

Color screen doesn’t add anything meaningful to the experience and in the sun, at least the 4px screen was terrible especially if you wear sunglasses while driving

Question - Isn't the only T-FHSS SR compatible model currently available the R334SBS (which has an external antenna)? If this is the case, while yes it would be true that Futaba has antenna-less offering(s), the response time gap would be an even wider deficit than an M12S-482 combo.

We are back to personal preference. Having gotten away from antennas with the 482, I personally don't ever want to go back to them. No antenna AND faster/est response time is a win-win.

I race left handed and the M12S in that configuration is awesome, plenty of room. I installed a lipo battery in it so it goes for some time before needing a recharge, and with the Reaktor 250 charger that doesn't take very long. I have never enjoyed racing as much as I do with the M12S, I feel like I am "in the game."

I have both, 7PX is a awesome piece of hardware. I just love the software too.

Which one feels more comfortable/faster?

I like the 7PX, The hand grip of the m12s comes off. The Futaba is faster and feels like a better piece of of hardware.

They have also upgraded the ability to use a lipo

Faster, how can you prove that? Please bring out the sheets.

How does that charger stack up to a Hitec X2?

theoretically 7PX SR mode should match M12S' SSL and SSR mode. Both are based on the narrowband PWM with neutral at .76ms instead of the 1.5ms neutral for a standard digital servo. Both will need programable servos to achieve the fastest response so that requires more expensive servos. I think your choice should be based on your ergonomics and feel preferences. M12S is slightly less expensive at the moment but 7PX are compatible with cheaper receivers using slower protocols which is great if you have bashing vehicles or a large fleet. 7PX will have significantly less battery life than M12S if you do not turn the screen off when driving or do not use a LiFe Pack. Both radio supports antennaless receivers but the form factors are different. I do not think the 7PX SR capable antennaless receiver has been market released yet, but it has been shown in hobby shows already so I expect it to be out soon.