Upgrade recommendations from EOS Rebel T3i

[nanda015]

My girlfriend currently uses a t3i, I want to surprise her this Christmas with a good upgrade, unfortunately my knowledge about canons are a little lacking, currently I use a mirror less Nikon z50, I'm trying to get her a significant upgrade over the t3i she has now, while still retaining the lenses she has for it, any ideas? I thought maybe I could go for a r series canon or a m series camera with an adapter, but I'm just not sure, maybe a mirrorless camera with an adapter?

[deebatman316]

The M system is a dead end and discontinued. I wouldn't look into a DSLR camera. They have been replaced by mirrorless cameras now. Do you have a budget to spend on a new camera or kit (lens + camera). For APS-C there is the R100, R50, R10 & R7. I have ordered them from low end to high end for both lines. For Full Frame they have the original R, R8, R6 Mark II, R5 & R3. You still may be able to find the original R6 selling and the RP. Which have been replaced by the R6 Mark II and R8 respectively. 

[rs-eos]

Agree with Demetrius that the M-series cameras should be avoided.  No future to them.

Do you have a particular budget in mind? Also, what lens or lenses does your girlfriend have with the camera?  You could go with a Canon EF-to-RF adapter so as to be able to still use those lenses on an R-series camera.  Or, if budget allows for it, to also pick up at least one new RF (or RF-S) lens.

Having said all that, the least expensive R-series camera is the EOS R100.  Followed by the EOS R50, then EOS R10.

[Tronhard]

Like my colleagues, I would stay away from investing in the M-series Canons as they have been officially ended as a product line.  The DSLR range is withering as well, as Canon concentrates on the R-series MILCs.
As regards which of these is best, the first things we need to know are:
1. Budget - no point in suggesting gear you can't afford
2. What lenses she shoots with now. 
3. What subjects does she like to shoot?   That will give us some idea of sensor and lenses.
4. Is there anything she complains about, or really likes about your Z-series MILC?