What’s the best consumer level FPGA that I can buy to experiment with? One that has the highest speed of final product and most memory etc? What’s the best of the best?

Xilinx leads the pack (now part of AMD). There are boards based on their MPSoC family at very good prices (Ultra96 for around $250, only real thing that's missing is Ethernet but it has WiFi). Embedded ARM cores and ultrascale+ fabric. Very hard to beat.

Zynq 7000 family is a more affordable entry point, but resources are more limited in every regard, and uses a slower, more power consuming process.

Lattice-based boards are great because they are supported by open source tooling, and available in many indie buildouts (ECP5 or or ice). They are not so high end though, by far, compared to Xilinx parts.

Intel (ex-Altera) seems to have good stuff, but not as advanced as Xilinx. They are used on the mist and mister systems for hardware retro game emulation, a quite active scene.

The answer depends on how much you want to hate your tooling. The fastest stuff uses all proprietary, heavily licensed/restricted tooling.

I like the lattice stuff for experimenting because you can do the whole stack with free software.

For beginners coming from software side, I highly recommend the official lattice boards like ice40 hx8k (by axelsys).

They are cheap and are supported by the FOSS toolchain. So you won't waste money or wrestle with crappy and/or expensive commercial tools, and can concentrate on learning FPGA.

My two gotos have been the Mojo v3 (Spartan 6 LX9) (fairly old at this point), they can be had for $30 on eBay and have a built in programmer, and the Alchitry Au (Artix 7 35T). It's $100, but it's nice and compact and has a ton of gates. Also has a built in programmer and 256 MiB of DDR3.

Neither of these have high speed serial interfaces (for things like ethernet, PCIe, HDMI, etc.), but they're fun starting points.

I'd love to get into making my own FPGA boards, but man, BGAs are scary from a hobbyist perspective. The Spartan 6 LX9 is neat (from a hobbyist perspective) in that it's a big QFP.

I am not really sure what you’re asking. You could get a Xilinx RFSoC, but the development board is like $10,000.

If you’re just wanting to learn and experiment, like myself, then Digilent makes a lot of nicely packaged boards. The Nexys A7 is a capable board.

You can try TinyFPGA. It has a fully open source toolchain and a lot of examples on Github. It is also quite inexpensive.