I've not tried Adguard, but I was fond of and a user of Ghostery before the reveal that they were blocking ads on one hand, while also reporting to ad tech companies.
As for how to compare all three of them… that's hard to say. All blockers hit the major eye sores on popular sites like Reddit, Google, and Facebook. Day-to-day you're not going to notice a difference.
The complication becomes that Blocker 1 may block ads A, B, and C, while Blocker 2 blocks ads A, B, and D. One is not necessarily better than the other, but more that they have different scopes.
Then there's the fact that some sites refuse to load content if they detect you aren't loading the ads. It's not really the adblockers fault even if it's a consequence of using them.
Unfortunately, running multiple adblockers has a non-zero chance of causing unintentional conflicts where both blockers try to attack the same ad.
Which brings me back to my method of having my cake and eating it too. By using a VPN, a custom hosts file, and a browser extension, I have multiple non-conflicting layers that protect me better than any one solution.
You’re over thinking it. The theme only needs to be inspired by LCARS, not 1:1 recreate the on screen experience.
So some secondary colors, some nostalgic font choices, and creative liberal use of rounded corners would be a good non-invasive first step.
While I have no experience theming for Lemmy, I’ve done theming for phpBB for some personal projects. With the staff’s blessing, I wouldn’t mind taking a stab at it.