I believe -image is irrelevant now compared to what it did for GW1.
GW2 always downloads all the files before launch (if any are outstanding), rather than the GW1 way which was to immediately download only what it needed at that moment, and then download everything else in the background. So if you've launched GW2 and got into the game, you have all the files - it's all or nothing for everyone.
As far as -repair or -verify, these are maintenance/troubleshooting commands for when you suspect the file is corrupt in some way, rather than to be used as a regular part of running the game, or optimising anything. I can only think of 3 occasions where these commands need to be used - disc corruption, memory corruption, or a bad download, and all 3 of those will show symptoms in-game (crashes, corrupt visuals, etc) and possibly out-of-game (BSODs, other instability) to prompt you to troubleshoot, and fixing the hardware/drivers/OS should probably be much higher up your list.
In other words, the game should take care of itself. Running this kind of operation every patch is just stupid, and if you're getting slowdowns, this is probably not the solution unless you're HDD is on it's last legs, in which case you should probably look at replacing it anyway.
If you're looking for a tiny bit more performance on a HDD (not a SSD), you might want to check if it's worth defragging the volume GW2 lives on, or maybe defrag just the gw2.dat file.
Contig is another tool you can use to defragment single files.
I can see defragging helping a bit if gw2.dat is severly fragmented, as for some situations such as WvW or big fights with lots of people in general there's lots to load, and this will only help on non-SSD drives. More generally though, if you've got poor performance you need to find the bottleneck that applies, it might be loading, or it might be CPU or GPU, and there's tools you can monitor to figure that out.
As the big dat file gets patched it becomes more and more fragmented (spread out in small chunks around the disk). This makes it much slower to load game data from the disk. This will be most noticeable if you have a disk without a lot of free space. The same thing happens in other games such as TF2, however in that case steam has a built in optimizer.
For GW2, if you don't want to run a full defragment you can get tools that are able to defragment single files. I use contig every so often myself.