I have been using the g2 for many years, probably used around 3 of them, however its hardware is aging and I have moved onto other devices, though I still keep my G2 as a backup phone. I am sure many of you here are die hard qwerty fans like me, and would apprecaite an upgrade, as such I decided to list a few phones that could be upgrades to your g2 below.
Phones I have personally used:
T-Mobile mytouch 4g slide
Dev support for this device is pretty much dead, as the last active dev for it spoilt his phone, however there's still a 99% functional cm11(4.4.0) rom for it. This device feels really fast compared to the g2 and it is an overclock monster. Its keyboard doesnt feel as comfortable as the G2's, but it is still decent. You can easily unlock it and use it on any GSM network, it takes a mini sim and supports much higher 3g speed than the g2. It also has a removeable battery and sdcard slot.
Verizon Droid 4
It has official cm11 support and an actively developed kernel. It is very fast thanks to its 1gb of ram, apps no longer get killed due to low ram. It has the best keyboard on the market, and once you've used it, there's no going back. It takes a micro sim and you can use it on any GSM network outside the US, with a few exceptions though. Unfortunately its battery is not removeable, however it does come with a sdcard slot and has 8gb internal storage. Used ones are dirt cheap on eBay.
You can choose the Droid 3 if removeable battery is a must for you, everything is the same as the Droid 4 except no ffc and a slower clocked cpu, and no LTE if you're using it on Verizon. It takes a mini sim
You are reading it right, yes, Blackberry. First of all, it has the fastest hardware among all the phones here, its OS is pretty much stock android with an overlay, and you can install just about any android app directly onto it (play store doesnt't work, so only sideload), so essentially it can be classifed as an android phone. It has a really good keyboard which is expected of a Blackberry, removeable battery and sdcard slot. If you want LTE you can just get the variant which works with your carrier's frequency.
Phone which I have not used myself
T-Mobile LG Optimus F3Q
I can't comment much on this phone as I have not used it myself, it is currently only available through T-Mobile. It has the largest battery among all the phones here. As at the time of this post, it does not have a forum on xda, however, someone has managed to root this phone already (with a few hicups), you can read more about it here
I hope you guys will find this guide useful, it shall serve as my contribution to this forum as being on it for so long.