Sounds like I've been invoked.....
As Tha_Ape says, the A148 is a situational aircraft. Go that way only under a certain set of circumstances. As long as you're a big boy with enough cash to buy anything, you shall buy the best thing money can buy. Which is the Ejet. All other modern regional jets are inferior - but they all have their niche which makes the useful anyways - in the right set of circumstances. Bar the TU334 which is just useless. Run away from the TU334. Consider everything else in the category, even ARJs(though their uses are limited)
A148's niche is its insanely low price. Especially when you're the only one to go that way. When you can't afford to buy new ejets, what you spare by leasing those babies,
even new, or even better purchasing them for trinkets, more than makes up for increased fuel, flight, maintenance and commonality costs.
First time I flew them, I was playing in Europe, and 148As were enough for 80% of my routes. I could secure them for a low price. I had hundreds of CRJ100s that were getting old, little too small, and were still costing me 50/60k$ per week in leasing costs. My weekly pretax was around 10M$. Counting the tax, I could either order new leased CRJ700s, or new owned A148s. And one can compare.
A148 has 2 more seats. Not bad, but not a game changer either.
A148 costs a few thousands more weekly in maintenance + comm - compensated by insurance.
A148 costs 10/20k$ more in fuel, and the longer the distances, the worse. It's simply a plane never to fly beyond 1800NM. But CRJ does not go any further than 1800NM, so it's fair game.
Leased CRJ700s were costing me around 100k$ per week. Brand new owned A148s were costing me 7k$ weekly in depreciation(without cash loss). That's how I conquered Europe's regional market - with more than 700 A148s(before the ukrainian achievement was actually a thing

)
Differences with Ejets would be even more impressive - in both directions. If you can actually pay the Ejet upfront, the difference in depreciation & insurance won't be enough to justify the A148. If owning Ejet is not within your capability, then leasing - or even better, owning - new A148s really can fuel your growth. The common wisdom to "buy new, lease old" does not apply to such dirt cheap planes(same with A140s, if you need something even smaller).
Of course, A148s has other drawbacks. Its larger(A158) version lacks range, and its cargo version(A148T) can't carry heavy cargo. It's heavier than its counterparts, which has an often overlooked effect upon flight costs. Still, as a growth plane, it absolutely kicks ass. If you're already big, play the big boy, and go EJet.