There are several ways, only one is perfect. This list is in decreasing order of quality and the spirit of Roleplaying as it were.
People around a table, minis/tokens on a mat: As I've said before Minis on a Mat is, for all intents and purposes, the default and best roleplaying set up. Tokens can be subbed in if you're broke. Tokens don't cost much, in a pinch you can use pennies, nickels, dimes, and quarters.
Virtual table top, everyone has camera: This is a considerable step down as in-person interactions grant nuance that even the most high quality camera can't properly express. Even with lavish level design and model design that put a random person's mini collection to shame, online interactions pale in comparison. Someone who thinks minis on a mat is inferior to VTTs because of graphics quality should really just be playing a video game. There is an incredible need for MoaM, but there is not a quality requirement as they are merely placeholders for mental images and an objective view of the scene being played out. As a picture is worth a thousand words, Minis on a Mat is worth a lot more than that.
-----Good to Neutral Demarcation Line-----
Virtual table top, few/nobody has camera: Basically all the failings of VTTs over in person, along with the added problem that some people are going to be a bouncing avatar or first letter of their name instead of the simulacrum of human interaction that a camera can provide.
People around a table, theater of the mind: A form of Minis on a Mat is so integral to RPGs that when you take them out of it, even if you're in person, you take away a huge portion of the experience. There are games that don't support Minis on a Mat because their designers are lazy. These are not RPGs. They are group storytelling activities. Games have props, tokens, cards, balls, dice, etc. Games have something to play with. A 3rd party can see you playing a game and if they know the game, know what's going on.
-----Neutral to Useless Demarcation Line-----
Conference Call, theater of the mind: More things taken away, more of the experience is diminished, just as before.
Play by Email, graphic designer GMing: When you get to this point, you're stepping out of roleplaying entirely. There is no world where PbE or further down this list constitutes immersive roleplaying. This is a mockery of roleplaying, or to put it nicer a slow simulacrum. These are obviously better than text only, but just barely, and the juice is not worth the squeeze from the GM chair either.
Play by Post, graphic designer GMing: Worse than PBEM because at least with PBEM you know people are getting the responses. With PbP, there's a chance participants won't even sign in and look in days/weeks/etc.
Play by Email, text only: Snore
Play by Post, text only: Dies after a week or less.
Solo "RPG" Play: This is purely a creative writing exercise. There is no roleplaying or gaming going on. It doesn't even really deserve to be in this list any more than Poker, Basketball, or some other activity that isn't remotely involved.
