I ported my number to Google Voice (cost me $20) and then purchased a $30/month T-Mobile prepaid plan with 5GB 4G, and it works great.
I don't call often, but when I do, 4G works great and Edge is acceptable, but I mostly call when on WiFi. Texting works great as well with my GV number. I use the app Talkatone for calling and texting with my GV #, and the free version provides ample call quality for me, but you can upgrade for a monthly fee to get improved quality and compression and whatnot. Talkatone also allows me to send MMS's, which is a plus.
So I'd suggest using GV, although I really hope they don't pull the plug on it, but that doesn't seem to be the case.
EDIT: also I started the port process to GV at night, and the number was successfully ported around noon two days later.