) I can safely say that My Little Pony: A New Generation was great! 
And here are my random thoughts:
MLP villain rankings: Lord Tirek · 8:27pm Feb 16th, 2019
0/10 - AWFUL (unsalvageable, never should have been made, wouldn't recommend to anyone)
1/10 - HORRIBLE/BORING (tedious, hurts to watch, a bore, no reason to watch him/her, whatever positive things about him/her are tiny and not enough)
2/10 - VERY BAD (slightly less terrible, maybe there were one or two things you liked kept him/her from being a 1 but still very painful)
3/10 - BAD (the kind of bad where you're checking your watch over and over to see how much time is left before he/she gets off the screen)
4/10 - MEDIOCRE (not awful but not really that good either)
5/10 - EH (average, didn't love or hate him/her)
6/10 - DECENT (the first positive rating on this list, fine overall, glad you saw him/her once but wouldn't watch him/her again)
7/10 - GOOD (enjoyable enough that you'd maybe watch him/her again in future, had some noteworthy flaws but is overall a worthwhile villain)
8/10 - GREAT (a solid, enjoyable villain, very entertaining)
9/10 - EXCELLENT (very engaging, awesome, you definitely recommend to anyone)
10/10 - MASTERPIECE (extremely engaging, an absolute must-see)
Lord Tirek
I think this is the closest MLP is gonna get to having Satan as a villain.
While his motivations may not be that fleshed-out, I don’t think they need to be. Tirek’s appeal mainly comes from the spectacle and how refreshingly simple his design is. No played-out villainy tropes, just a power-hungry brute who wants nothing more than to destroy and conquer all once he reclaims his strength. Not to mention he’s one of the most genuinely scary villains in the whole show. He escapes Tartarus extremely weak at first and starts small by draining regular ponies’ magic, gradually working his way up to Alicorn magic as he heads for Canterlot, growing bigger and more powerful as he does so. When you think about it, most villains like Chrysalis gloat about starting with Ponyville/Canterlot then all of Equestria but they never actually get that far.
Tirek, on the other hand, was midway through conquering Equestria.
But what still makes him a tonne of fun to watch is, being a reimagining of an MLP villain from the original 80s cartoon, he’s also Tim Curry-levels of hammy (massive props to Mark Acheson's performance). Not to mention a manipulative smooth-talker who managed to dupe the spirit of chaos himself into helping regain his power, seeing how he knew Discord could’ve easily beaten/apprehended him in his weakened state. So he took advantage of the Mane Six still alienating Discord to appeal to his chaotic nature. Then Tirek drained his magic once he became strong enough to best him. And as Frenemies showed, Tirek’s smart enough to learn from the failures of others. And to top it off, he’s one of the few MLP villains who goes down fighting in his debut.
To put it bluntly, I love this guy.
9/10 EXCELLENT
LINKS TO OTHER VILLAIN RANKINGS
Nightmare Moon
Discord
Queen Chrysalis
King Sombra
Sunset Shimmer
Lord Tirek (you're already here, you plonker)
Adagio Dazzle
Starlight Glimmer
Midnight Sparkle
Gloriosa Daisy
Juniper Montage
Stygian/The Pony of Shadows
The Storm King
Wallflower Blush
Vignette Valencia
Chancellor Neighsay
Cozy Glow
PostCrush
Grogar
They really struck gold with this guy. He was scary, cunning, greedy... just a wonderfully realized bad guy.
I'd make a comparison to the Emperor from Star Wars: they're bad men who enjoy conquering and destruction in card-carrying fashion, but they're so charismatic and well-realized that the simplicity of their nature becomes part of their appeal instead of detracting from it.
5014644
Great, now I want to see Tirek say "Nooo, noooo, nooooo!"
5014651
Oh Lord. That would be hilarious. XD
If there's anything I liked about Tirek is that he managed to get Discord on his side through the latter's better nature, so props to that, and you do raise a good point about him conquering Equestria halfway.
5014651
"YOU WILL DIE!!!"
An interesting thing about Tirek is that in G1 he was the villain of the very first special: Rescue at Castle Midnight. And he was really dark. He blackmails Scorpan by threatening to kill Spike unless he has four ponies to power his chariot, and he seeks an unspecified "Rainbow of Darkness". Though darker doesn't always mean better, because he's still an 80's villain. He's evil simply for the sake of it and is just a monster the ponies have to defeat.
Tirek is more fleshed out as a character in his G4 incarnation, though I think his initial appearance made him a bit of a "Villain Sue" and his inclusion in the S8 finale really didn't amount to much. I like how S9 showed he was practical though, that unlike other villains he could learn from his mistakes.