Best for mostGregory Hays · 2002
The version most people are quoting when they quote Marcus. Hays writes in plain, forceful modern English — you forget you're reading a translation. The tradeoff is real: he smooths over some of the Stoic technical vocabulary, and the notes are thin. For a first read, that's a fair trade. This is where I'd start.
Best for going deepRobin Waterfield · 2021
The 2021 annotated edition. Waterfield translates accurately and then explains — footnotes that actually tell you what's going on, and a long introduction on Marcus and Stoicism. Less poetic than Hays. The one to own if you want to understand the book, not just read it.
Most literalRobin Hard · 2011
Closer to the Greek, with Christopher Gill's scholarly notes — and it adds Marcus's surviving letters to his tutor Fronto, which you won't get elsewhere. Measured rather than punchy. Best for a second pass, or readers who want the philosophy precise.
Best balanceMartin Hammond · 2006
The accurate-but-readable middle. Hammond keeps more of the Stoic terms intact than Hays without turning stiff, and Diskin Clay's introduction is excellent. If Hays reads too loose and Hard too dry, this is the one to reach for.
Most affordableGeorge Long · 1862
The 1862 translation, out of copyright, in Dover's inexpensive edition. The English is Victorian — 'thou' and 'thee' — so it reads older than it needs to. But it's complete, it's a few dollars, and the same text is free online if you just want to start tonight.