More power is always better! Just ask Tim Allen (TV show "Home Improvement")

Many of the studio strobes have multiple power levels; some as simple as
half and full-power, others have a continously variable output power level.
Ya pays your money 'n' ya takes your choice!

When all else fails, carry a couple white hankerchiefs. One layer of a white
hankerchief over the strobe is about one stop of light reduction. If the
strobe has a hot modeling light, try not to start a fire with the
hankerchief!

Ken Hart

I've started off like you , with a Vivitar shoe mount flash .
And move to a Novatron 500 watts Kit about 10 plus years ago.
Recently I have move up to a Calument Travelite 1500 watts Kit .
I wanted to shoot with an aperture of f/32 with my 4x5 view camera,
the Novatron was not enough power.
All power pack or monolite have adjustments to lower the power .
Or use umbrella to bounce the lighting reducing the intensity .
You can also move the lighting further away from the subject .
I did not regrets getting more power, but did getting less power.

Good Luck in your search .

I did what you want to do...I'll tell you what I did and why, maybe that'll
help you to make up your mind on what to do.

First, I looked at power pack systems and monolights and decided on
monolights for several reasons:
1) Power packs usually allow you to have the power symmetric (1:1) between
channels or asymmetric (usually just 2:1) between channels...if you have
unlimited space to physically move lights back and forth you could probably
live with that, but I couldn't in a small space so I chose monolights which
can be set independently to any power level I choose.
2) As I was looking at higher total power, the monolights were also
advantageous as I could distribute the load on the wiring of my house rather
than needing to wire a 20A or 30A circuit for the power pack
3) I liked the redundancy in that if the power supply of one light failed I
could still use all the other lights..
4) I could add as many "heads" (more monolights) as I wanted whenever I
wanted
5) I decided to get as much power as I could since I could always reduce the
light (dial-down, reflect, ND on light, ND on camera, etc.)

Features that I looked for in monolights and other considerations:
1) Proportional modeling light so that I'd have an idea what the lighting
would look like
2) Power variable over several f-stops
3) Good availability of reflectors and other accessories and priced
reasonably
4) UV-coated flashtube so that objects being illuminated wouldn't fluoresce
5) Established and stable company because these things aren't cheap

Some of the companies you have to choose from are:
Photogenic
Bowens/Calumet
Balcar
Elinchrome
Speedotron
Novatron
White Lightning
Broncolor
Comet
Dyna-Lite
Multiblitz

I went through the list above checking out products and decided on some
Bowens studio flashes.  I ruled out some of the above due to features, cost,
versatility, distribution, etc.  But all of these makes do get used
professionally.

Good luck.