There could be biases in this answer. I would say Public Mobile by a country mile. No zones vs zones is a major reason for my answer.
The current Lucky Mobile $40/4.5GB plan has no zones. It is completely a Canada-wide plan on the entire Bell Mobility network.
lucky mobile vs public mobile both 4.5 40 dollars same as publice no restrictions
I would say this depends on customer preference on which company to deal with, customer service approach, and Public Mobile's reward system.
Other than those things, the plans are very similar.
To me, the very major advantage that won me over is the option of enabling a full-fledged LTE plan on PM whenever I need it. Plus the roaming packages at PM, which Lucky doesn't have, so I don't have to get a temporary SIM card whenever I travel to the States. Those two things are what ultimately convinced me to move to PM yesterday (although the move was actually sparked by seeing Lucky mobile's ad and researching further, then finding that PM has a response which is better in my book).
Also, Lucky is owned by Bell. Its reputation doesn't seem to be as good as that of Telus, which PM operates under.
Contrary to some of the answers above, Lucky runs on the exact same infrastructure as PM, they also use LTE and cap it to 3G speeds. They both use the combined Telus + Bell infrastructure, so the reception will be the same. The difference is PM also offers plans with unthrottled LTE. I actually moved from Chatr (the third competitor), which actually runs on a more limited 3G infrastructure with no access to LTE whatsoever. You get 3G capped to 3Mbps over there, on a Rogers network, and with zones (Canada-wide plans are not competitive at all in terms of pricing, and not even advertised much).
Bringing this thread back.
Right now - Sep 2 - If I were a new customer looking at the $25 plans, I would probably be going to Lucky since they have unlimited 128kbps throttled data once your main 1GB data is used up.
People have reported using the slow speed and can still use Google Maps, stream audio, radio, and of course email and messaging is fine. Video is pretty much not working. So unlimited data on a $25 prepaid plan, that is a big difference and for most would more than make up the $2 autopay that PM gives. And as crude as it is, Lucky does have a call in centre.
If your calls will be from a Lucky Zone to a Lucky Zone then Lucky can cost less.
If your calls ate to or from anywhere else then PM will cost less.
PM gives more Rewards (AutoPay, Loyalty, Referral, Community), they're all small but they all add up.
Lucky only gives one-time Referral Bonuses... sometimes. More short-term gain... up to a limit... if you can keep bringing them in.
PM never charges for admin stuff - account activation/suspension/reactivation, address/info change, phone number change, etc - but Lucky does.
Lucky offers Data to keep trickling beyond maximum allocation. PM doesn't. Maybe a Big Deal for some Data users, although I suspect they'd generally be happier with bigger Data plans (in which case they'd generally be happier paying less on PM).
PM recently gave everyone a chunk of free Data. Maybe it'll happen again, maybe it'll never happen again. Lucky has never issued comparable gifts.
PM service/support model sucks when you actually need a problem fixed. Lucky has kiosks and people who can resolve customer problems face to face.
I don't think Lucky has zones anymore.
I'm not leaving PM - I have too many ongoing referral credits. I'm just looking at it from a first time client point of view.