Lens choice depends very much on what you want to photograph. You haven't told us, so we're only able to give some general answers.
But first, any Canon EF or EF-S lens that fits your T5i will be adaptable later for use on Canon R-series (newer) or M-series (older) mirrorless cameras. That said, it is better to use the native lenses for each of those systems, as they are often newer, improved designs and can be smaller and lighter than adapted DSLR lenses. There aren't a lot of EF-M lenses for the older M-series mirrorless. More likely you would be looking at the larger and growing selection of RF and/or RF-S lenses for the newer R-series cameras. This because the R-system is gradually replacing the previous systems (the M-series and their lenses, and the Canon DSLRs and their EF/EF-S lenses will be phased out over time). Note that RF and EF-M lenses are NOT interchangeable. Neither can be adapted for use on the other's system cameras.
Lenses choice depends upon the purpose...
- A general purpose "walkaround" lens is usually a mid-range zoom like the kit 18-55mm or the step up to the EF-S 18-135mm (18-150mm avail. in RF and EF-M versions). There also are more premium alternatives in the EF-S 15-85mm and EF-S 17-55mm f/2.8. The 15-85mm might be a good choice for someone who wants a little wider than the usual kit lenses, but doesn't want to get a separate ultrawide (see below). The 17-55mm has a larger, non-variable f/2.8 aperture so would be a better choice for someone needing to shoot in lower light conditions frequently (though there are other solutions for that challenge). A very affordable alternative that just doesn't go very wide is a used EF 28-135mm. That's an older lens design, among the first lenses to have IS, but was in production for more than 20 years, is quite capable and was sold a lot as a kit lens for various cameras. There are a lot of them available on the used market and good copies can be found at relatively low cost. Since 28mm isn't very wide on an APS-C camera like a T5i, the 28-135mm might be best if complemented by some ultrawide lens.
- Wide angle lenses are useful for a variety of things, but are often chosen for landscape, cityscape, seascape, architecture and a few other specialties. This is not to say this is the only type of lens used for those purposes or that wide lenses are only limited to these purposes. Just that these are some popular uses. There are a variety of wide angle lenses available. Just to narrow it down a bit... Canon EF-S 10-18mm and EF-S 10-22mm are a couple very good ultrawide zooms. The 10-18mm is a newer lens, with IS, and quite affordable. It's also rather plasticky. The 10-22mm is brighter lens, with larger maximum lens aperture, a bit better build and faster USM autofocus drive (the STM drive in the 10-18mm certainly isn't slow... ultrawide lenses focus quickly simply because they don't need to move their elements very much to do so). Either lens can do you proud. There are a number of third party lenses... both with and without autofocus... at a wide range of prices.
- Longer telephoto lenses are popular for many things including sports photography, wildlife, "birding", and more. Short telephotos may be preferred for a lot of portraiture. There are both telephoto zooms and "primes" (lenses that only have a single focal length, that don't "zoom"). I shoot a lot of sports and some wildlife, so I have a number of telephotos: two 70-200mm, four 300mm, a 100-400mm and a 500mm. I also have 1.4X and 2X teleconverters that I use with some of these lenses. For more portrait purposes, I also use 50mm (which is a short telephoto on an APS-C camera), 85mm and 135mm.
- Specialty lenses include macro/close-up, tilt-shift for perspective correction, fisheye for uncorrected ultrawide effects, ultra-large aperture lenses for dreamy background blur effects and more.
So decide what you want to shoot, then choose the lens for it (or ask around for recommendations). Or if you just aren't sure what you'll be doing, get a generalist type of lens, go shoot a lot and find your limitations.... then look for lenses (or other accessories) that will help you overcome those limitations.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
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