So what is a good place to start? Well, there are some tasks that either aren't easy or require a lot of setup with power tools. I think those are good places to start: find hand tools that do things that are hard or time consuming with power tools, and easy or fast with hand tools. So here's my list, in no particular order.
- A shoulder plane. This one makes a lot of the lists, for good reason. Get a wide one; 1", 1 1/2", something like that. This can tweak tenon shoulders or faces, take a tiny bit off a rabbet that's not quite deep enough, things like that. With sufficient practice, it can cut a rabbet in the first place, either following a pre-cut shoulder (probably cut with a table saw), a fence, or a knifed line. If you cut a lot of tenons or rabbets, this is a good plane to have.
- A rabbet plane. Something like the Stanley #78 is a wonderful first plane. With a fence to control the width, a stop to control the depth, and a nicker to allow it to work cross-grain, this is a fantastic tool for cutting one or two rabbets. If you have gauging blocks, set up is easy: just set it blade down on the bench with a block under the depth stop to set depth, and on its side with a block under the fence to set width. Now cut the rabbet. Setup should take under a minute. If you have dozens of rabbets to cut, use a table saw with a dado stack or a router table or something like that. But for a few rabbets, this plane will cut them fast enough that you'll still finish quicker than you would setting up the power tools. If you make a lot of small projects with one or two rabbets, this is a good plane to have. If you only do large runs and need dozens of identical rabbets, pass it by.
- A block plane. Personally, I don't much like these, probably because I don't have a good one. But they're nice for chamfering edges, tweaking joints that aren't quite level, and things like that. They're small enough to put in a pocket, so there's no reason to ever not have one in easy reach. If I were buying one new, I'd buy either a low angle model or one with an iron that goes all the way to the outside edges so I could use it instead of a shoulder plane for cleaning up tenons.
- A grooving plane. This could be a combination plane. It could be a plow plane. It could even be an old wooden plane with a fixed fence that cuts a single width of groove at a fixed distance from the edge of a board. Whatever, it's a useful tool. Use it for grooving the rails and stiles of a door. Use it to cut the groove to hold the bottom of a drawer. Working in small stock, it's easier and safer than a table saw or router table, and for a single drawer or door setup is likely to be a lot faster. Veritas makes a nice small plow, and I've seen good reviews of the Mujingfang plow plane, which is a steal if it's actually reasonable quality. Again, if you make small projects with just a couple of grooves, or a lot of furniture with only one drawer, this is a great tool to have. If you're trying to outfit a whole kitchen, you should probably take the time to set up a power tool to do the job.
- Moulding planes. Now that I have a beading plane, I think everyone should have one. Mine is in terrible condition, but I can cut a bead in the edge of a panel in a few passes. Once I've got it cleaned up, that won't change, but it will jam less frequently and may be able to handle cross-grain if I'm careful. Bead the edges of your shiplap or tongue-and-groove cabinet backs. Put a bead into the outer corners of table or desk legs. It'll dress things up, and help protect the corners. I paid ten bucks for mine at a flea market, and it will be perfectly useable once I've spent a little time tuning it up. Doing beading with a router works, but I'm not actually convinced it works faster than a beading plane. If you like beading the edges of things, or you just see one of these in good shape cheap, buy it. If you pay ten bucks and use it half a dozen times, it was money well spent.
Once you have as many of those as you have a use for, think about a small smoothing plane. I like my #3 and #4; I use the #3 more often, partly because it's higher quality, and partly because I mostly work on small pieces these days, and they tend to vanish under the #4. Use your smoother to take out the ripples left behind by a jointer or planer, and to make very fine adjustments in the width of a narrow board. A jointing plane is better for that, but a smoother will work if you're careful.
Only once you have all of those would I consider a jointer plane and jack. If you're dimensioning with a table saw, jointer, and planer, you just shouldn't have much need for them. They're fun to have, and occasionally useful, but the others will likely get used on almost every project. A jointer and jack may get used a few times a year, if you're careful about what lumber you use.