During my games I spotted one strange thing - in all recommended item sets for junglers are Boots of Mobility item Boots of Mobility. I think that's big misconception and it renders many viable champions useless. Obviously, professional jungle players widely use Mobilities on champions, but is it really the only choice? On opposite side are Boots of Swiftness item Boots of Swiftness, those are bought rarely. Are they that bad?

In this little discussion I provide my own point of view with some in deep explanation.

Lets see about what I'm writing:

Boots of Mobility item Boots of Mobility:
800 gold
+25 movement speed. Increases to +105 movement speed when out of combat for 5 seconds.
Boots of Swiftness item Boots of Swiftness:
1000 gold
+60 movement speed.
Movement slowing effects are reduced by 25%.
Other boots:
1000 (up to 1200) gold
+45 movement speed
statistics and unique passives

Boots of Mobility - the cheapest of all boots, with excellent passive. It's great choice every time you want to walk around map doing stuff. The dark side of this choice is low basic speed value, equalling Boots of Speed item Boots of Speed.
Boots of Switfness - much higher price and useless passive (that 25% slow reduction is relatively low in values). The best thing of all, Swiftness provide the highest base value of speed and scale well with percentage Movement speed boosts.

It is obvious - mobilities are superior choice every time it's right choice. The only problem is included flat 20 slow comparing to other boots. We may swear - it's not a problem, then SkarnerSquare Skarner can't catch anyone, VolibearSquare Volibear just goes around on Rolling Thunder Rolling Thunder and RammusSquare Rammus can only roll from bot to top.
Question is - when that 20 units slow is not a problem and when it is?

Answer is suprisingly simple - if champion has considerable amount of gapclosers and ranged skills raw speed isn't really that important, because skills give enough means to stick to enemy, apply cc and secure taget for team.
Obvious champions:

On second hand there are champions without gapclosers. To stick to enemy they need to be faster and immune to slows. Many of them have percentage boosts to movement speed too.
Those are:

When playing those champions it's mistake to buy Mobilities. Without passive, on base movement speed value, those champions are nearly useless, unable to properly initiate and catch carries.
There are two solutions:

  • To buy Mobility and use them on early stages of games - then swap with others
  • or buy Boots of Speed and upgrade it later.

I puposely avoid supports' case and write only about limited number of champions. I wanted to write about items, not strategies or champions. Anyway I think, here should be another list of champions, champions I'm unsure of.

  • AatroxSquare Aatrox , actually I recommend Swiftnesses or other boots. Aatrox should stick to enemy hitting them with autoattacks, not pursuing slowly
  • Cho'GathSquare Cho'Gath should hit q, then speed doesn't matter
  • MalphiteSquare Malphite has movement boost from q, and sticks to enemies easily, but he can still achieve better performance with more reliable movement speed
  • NautilusSquare Nautilus has one gapcloser and ranged skills so Mobilities can be a choice, but it's better to get into mid of enemy team and wreck them there
  • NunuSquare Nunu  really needs movement speed, but for early domination Mobilities are great
  • Xin ZhaoSquare Xin Zhao  has 1 gapcloser and lack of easily applicable cc, but with early domination Mobilities are good choice. Although, in late game Xin should change boots
  • WarwickSquare Warwick has % boost and only one gap-closer, but Mobilities aren't that bad if one is farming and ganking only with ultimate

Boots of Mobility are part of static domination of junglers like Lee Sin. With really low price and great passive it's the best and obvious choice if champion can play over that 20 movement speed reduction.

But, if you already took another champion into game, don't commit mistake and take proper Boots. With champions like Nasus or Volibear running around in circles unable to pick up any opponent your team plays 4vs5.