Snap on ratchets are worth the money - if you do this for a living.
Otherwise not so much.
The exception to this is resale value. A used Snap on ratchet is worth about half or better of what it cost new, other brands don't really hold their value like that.
I don't think most people sell their ratchets so this probably isn't a huge factor from a practical standpoint.
I'm not big on the comfort grip thing. I have a couple and yeah, they feel kind of nice when you first pick them up, but I don't really pay much attention to it after that.
Its not like I'm sitting in it all day or sleeping in it. From a functional standpoint it doesn't matter, unless it slides around or comes off, and if its not there it can't do that, so I'd skip it. The couple I do have are because the truck only had ones with comfort grip when I decided I needed them.
As far as style of ratchet goes, at least for me, I look at what I need it to do and how close it is at hand, along with what sockets I have handy.
If I have to go out of my work area to do something and I'm not sure what I'll need, I'll grab a long handle flex head snap on 3/8" ratchet, snap short and medium extensions on it, and grab a rack of metric mid length sockets. That will cover me for most situations, is compact, and easy to keep track of.
If I'm pulling an engine, I will already have universal (flex) impact sockets out and in use, so if I need a ratchet I'm going to grab a long handled straight one. Because flex head ratchets and universal sockets don't play well together and I'm likely to pinch the living Sh** out of my hand.
So in my opinion, you are going to need both straight and flex ratchets. Flex are handier, but won't work in every situation but will for most unless you use a lot of universal sockets.
Most of the mechanics I know, or have known, will grab a long handled flex ratchet by preference the majority of the time as well.
I've never had problems with a flex head ratchet flopping around while I'm using it. You would have to be way off from any practical angle for this to happen - or using a universal on it.
I also prefer a long handle over a standard one. The more leverage I have, the less force I have to exert, and if I have to exert more force I can with a longer handle.
I don't recall ever changing from a long handle to a regular handle because I needed to, I have had to switch to a longer handle.
Stubby ratchets are also very handy. As time goes by vehicle size goes down (ask an older tall person if in doubt), and engineers/manufacturers keep jamming more in.
A flex head stubby is almost a requirement anymore. If space is that tight you aren't likely to be using universal sockets.
You definitely want good high quality long handled ratchets, if one breaks while you are leaning on it hard you can get hurt, possibly badly.
With a stubby you could get by with a cheaper (but still decent) version, if used properly or at least reasonably you won't be generating enough force to hurt yourself badly though burning and pinching are still options.
Tooth count, like I said, things are getting tighter and I have on occasion wished for a shorter swing arc, but I don't recall ever wanting a bigger one. So all things equal otherwise, more is better.
I haven't really studied the matter by getting a bunch of different tooth count ratchets and testing them in various situations, but the 80 snap on's seem to work fine, the craftsman raised panel do not.
Also can't say I've ever found the shape of the head to be an issue either, don't care if its round or pear or whatever as long as it does its job. Rotoheads do have to be round I guess, but other than that I can't see it making any kind of practical difference.
Just starting out building a tool collection I would say its a good idea to cover as many bases as you can for as little expenditure as possible. Unless you are rich of course, but if you are rich pay somebody else to work on your vehicles.
My suggestion would be:
https://www.amazon.com/dp/B000V5G7LU/?tag=atomicindus08-20
or if you want to spend a little more:
https://www.amazon.com/dp/B00BTEXPDK/?tag=atomicindus08-20
If you really want Snap on, the first one I'd get would be an FLF80.
Used is around $75, a little less than the set of 4 gearwrench 84t new
New is $140, about the same price as the set of 120t gearwrench.
EDIT: Add about $15 or so for comfort grip it looks like.
If I was starting out I'd get the gearwrench 84t set, it gives me the long handle flex head which covers the most ground, and a stubby for tight areas, plus a 1/4" flex head and a 1/2" flex head, all of reasonable quality, lifetime warranty, availability, etc..., for roughly the price of a single Snap on.
Later on if you find yourself doing this for a living, or even a lot as a hobby or whatever you can always upgrade after you have all the other tools necessary to do this type of work.
