okay hear me out.
I played Junkrat since OW1 S2
love this character from my heart and how much rage he induces into my enemies.
no im not a onetrick but hes my most played hero with over 146hrs total playtime as of today.
second is Genji with 109hrs
my Total playtime exceeds 1400hrs
i like the LV.2 Perks … tho i only take the Tire Speedboost since its what the Ult was lacking ^^
Both Lv.3 Perks however are only downsides to anything i do with Junkrat.
1 Less grnade but they fly faster … sure but i can angle my shots on any map without compromise … dont need it and i loose 1 full shot of damage
And the Concussionmine Upgrade sounds nice but the 0.5 sec delay kills this perk for me 
soooo in total i only pick the Tire and refuse to pick Lv.3 since they are more a hinderence than an upgrade (at least in my book)