OP_not sure if you are in N. America or in Europe? BEst might depend on local support/rental/repair.
I live in N. America. I have Speedotron Black Line and Brown Line systems. Way too much of both for what I shoot these days. I like Speedotron for the simplicity of the system. They have enough types of light units that you can find a flash head for any budget, and any use. Durability and longevity are **the** hallmarks of the Speedotron brand. VERY "tough" equipment.
In Black Line, I like the 102A flashhead for long sessions: fan-cooled, big flashtube, 250 Watt quartz modeling lamp. For sine wave inverter use, I use their 103 flash heads (no longer made) which have no cooling fans, 150 Watt quartz lamp maximum, CAN use a low-Wattage 2-pin base incandescent lamp is desired to keep current drain LOW when running off the inverter. I have a couple 6-outlet, 2,400 W-s identical packs...NICE to be able to run 6 flashes off of ONE, single electrical outlet! I also have an 800 and a 400 W-s Black Line pack.
I like the Black Line model 202VF Variable Focusing flash heads. 250 Watt modeling lights, and a flood/narrow range of beam spread from any reflector. LOVE the Speedo mylar diffusers and grids. Steel reflectors, very solid.
For location work, the Black Line 805 power pack is nice, and FAST-recycle too. Has 4 outlets. For portable set-ups the little 405 is a great 3-head power pack. Very small and light, and useful on-location. The newer 4-outlet 1005 (1,000 Watt-sec) pack looks great, have used one once, liked it! SMALL! Black Line has 1/3-stop dial-click Up and Down fine adjustment,over a two-f/stop range or so, plus LOTS of power distribution options.
In Brown Line, the stuff is sooooo inexpensive, you can buy whatever you want for little money. Lighter cords, makes em easier to pack. I like the D1602 and D402 packs in Brown, the D604 is powerful and cheap. Flash durations are adequate, but NOT super-short. What I like are the light-shaping tools available in Speedotron Universal Mount; this is a system that has been around since 1939, and is American-built in Chicago. They do have 220 volt packs for customers outside North America. Brown Line reflectors and accessories in the Speedotron Universal Mount will work with Black Line, and vice-versa. Brown Line has limited, simple power distubution options.
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Dynalite is another USA brand of pack-and-head systems. I PREFER the power distruibution of pack and head systems AND the consistent color temp they have across the power levels. WHy pack and head? What is you NEED ONE flash that is a 2,400 W-s light? or you NEED 1600 W-s and then 800 W-s/ Or you NEED six, 400 W-s flash units. Or you NEED a 1200 and then an 800 and then a 400? If you own a Speedotron 2400 W-s pack with six outlets, you "already own" every single W-s power from 2,400 down to 100 W-s...no need to buy expensive monolights that have 1,600 Watt-second capacitors in them, no need for multiple powered monolights; with a pack and head system, you SAVE a huge amount of money by not "pigeonholing" a light to a specific Watt-second output level.
Dynalite has some very exciting smallish heads and smaller packs for location lighting. Dynalite and Speedotron are the two leading "arena systems" for large arena NBA and indoor sports events, and have been for decades.
Speedotron sells Universal Mounting brackets that can be bolted or screwed or epoxied on to light-shaping tools from almost any manufacturer. So, convert a beauty dish or light box to Speedo by bolting on a Universal Mounting collar.
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There is no one "best" system, and for "some" tasks, flash duration might be the key. For "some jobs", the ability to fire 1,000 full-power flash pops in 2 hours and NEVER have an overheated flash is a criterion. That's what Black Line does. Last major-major job I shot with Blackline was 104 corporate mugshots, all morning, one after another after another, in on-site makeshift studio with three 102A flash heads and a 2403B pack...did not miss a beat.