Given how many people have been talking about "mobility creep" and such, I decided to go take a look at how base movement speed is correlated to presence of mobility-granting champion abilities.

The champions are are separated into the following categories: No displacements (dashes/blinks); further separated into those with and without speed boosts Ground- or direction-targeted displacements (A); separated into ult and non-ult Object-targeted displacements (B); same as above

Numbers and such are at the bottom

General observations:

1. Champions with displacements on their ults have higher average movement (A: 339.9, B: 343.8) than those with displacements on non-ult abilities (A: 335.9, B: 341.7). Since one would expect champions with easier access to displacements to move a bit slower to compensate, this is quite reasonable.

2. Champions with ground/direction-targeted displacements (336.5) have lower average movement than those with object-targeted displacements (342.3). Since the former is more generally usable than the latter, this is also reasonable.

3. Champions with speed boosts (337.2) move faster on average than those without speed boosts (335.6). If only movement and mobility is taken into account, this does not make any sense, since there is no reason that a champion that can move significantly faster through an ability ALSO gets to move faster in general.

4. Champions with no displacements (336.7) have around the same average movement as those that have ground/direction-targeted displacements (336.5). This means that, at least movement-wise, ground/direction-targeted displacements do not incur any penalty to compensate. Furthermore, this means that champions that have object-targeted displacements (342.3) appear to get a bonus to movement speed rather than any penalty.

5. Putting observations 3 and 4 together, we see that champions that have no mobility tools whatsoever ALSO have the lowest average movement speed.

============================================================================== TLDR:
Champions with object-targeted displacements (like mobility poster boy Lee Sin) move the FASTEST on average. Champions without ANY mobility tools move the SLOWEST on average.

Numbers:

No displacements No speed boosts 325 (5): Anivia, Ashe, Kog'Maw, Soraka, Zyra 330 (4): Lux, Syndra, Twisted Fate, Varus 335 (4): Annie, Karthus, Morgana, Swain 340 (8): Brand, Heimerdinger, Malzahar, Mordekaiser, Taric, Veigar, Vel'Koz, Xerath 350 (3): Nasus, Olaf, Cho'Gath AVG: 335.6

Has speed boosts 325 (6): Blitzcrank, Jinx, Lulu, Miss Fortune, Orianna, Sona 330 (4): Draven, Teemo, Twitch 335 (11): Cassiopeia, Galio, Janna, Karma, Kayle, Kennen, Rammus, Sivir, Viktor, Vladimir, Zilean 340 (3): Evelynn, Nami, Ryze, 345 (10): Dr. Mundo, Gangplank, Garen, Rumble, Singed, Sion, Skarner, Volibear, Warwick, Yorick 350 (3): Nunu, Trundle, Udyr AVG: 337.2

Combined AVG: 336.7

Ground/direction-targeted displacement Non-ult 325 (7): Caitlyn, Corki, Ezreal, Lissandra, Nautilus, Tristana, Ziggs 330 (2): Graves, Vayne 335 (7): Azir, Fizz, LeBlanc, Lucian, Nidalee, Rek'sai, Shen 340 (4): Gnar (avg), Gragas, Jarvan, Sejuani 345 (4): Aatrox, Renekton, Riven, Tryndamere 350 (3): Kha'Zix, Shaco, Vi AVG: 335.9

Ult 330 (1): Ahri 335 (3): Fiddlesticks, Malphite, Zac 340 (1): Kassadin 345 (1): Hecarim 350 (1): Shyvana AVG: 339.9

Combined AVG: 336.5

=============================================== Object-targeted displacement Non-ult 325 (1): Kalista 330 (1): Alistar 335 (8): Amumu, Braum, Fizz, Jayce, Leona, Maokai, Quinn, Thresh 345 (7): Elise (spider), Irelia, Katarina, Poppy, Wukong, Xin Zhao, Rengar 350 (4): Fiora, Jax, Lee Sin, Talon 355 (2): Master Yi, Pantheon AVG: 341.7

Ult 335 (1): Urgot 340 (2): Darius, Jarvan IV 345 (3): Diana, Yasuo, Zed 350 (2): Akali, Vi AVG: 343.8

Combined AVG: 342.3