Hugo is popular with the Attack based clans especially Montana (the 6 attack gets them above the 8 attack minimum) and it creates a larger attack gap meaning you can 0 pill every round the the opponent will have to spend generally atleast two pills each round to get above the attack gap.
Eyrik is more associated with the Power clans as he makes the power gap bigger. If you use Nanook with bonus and Eyrik with about 4 pills she will 9 times out of 10 dominate 5-6 pilled cards because with 10 power and - 1 power on the opponent she is nearly unstoppable.
Hugo suits people who like to pill 1-4 most rounds. Eyrik is more of a Nuke card where you pill 5-7 on certain rounds. With this being said I have used Eyrik to pill only a little every round and vice versa for Hugo. It depends on your play style. But when it comes to low pill battles Hugo obviously works better, when it comes to high pill battles Eyrik obviously works better. I prefer Eyrik personally but both are wonderful cards and the only way to find which suits you more is to try both of them out.
Pretty much what Mr Intellijent said
Hugo is almost perfect with Montana due to the bonus and pill sucking tendency of the combo but the same can be done with sakhrohm, Uppers, Junkz, or Sentinel
Eyrik does make an inmpact with similar power clans like Ulu Watu and Bangers, however it's true beauty lies with the All Stars. Eyrik turns this entire clan into a brute force because now every card your opponent plays is likely having -3 power. This combos even better with cards llike Kang or Spudd that can add attack manipulation on top of that.
The first option is more budget friendly (to a degree) and is better for people that wait for the opponent to make the mistake wheras the second option is slightly more costly but goes better with a play style of people who like to overwhelm opponents and make a fatal blow that the opponent just can't recover from.