The following applies to MAAS
- hardware enablement kernels (where an 18.04 LTS will upgrade and use the 18.10 kernel in time, then 19.04, then 19.10, then finally 20.04 which can be useful for very modern hardware) low
- low latency kernels (see following)
More kernel options can be seen via https://help.ubuntu.com/community/UbuntuStudio/RealTimeKernel
-generic kernel - this is the stock kernel that is provided by default in Ubuntu.
-preempt kernel - this kernel is based on the -generic kernel source tree but is built with different configurations (settings) to reduce
latency. Also known as a soft real-time kernel.
-rt kernel - is based on the Ubuntu kernel source tree with Ingo Molnar maintained PREEMPT_RT patch applied to it. Also known as a hard
-lowlatency kernel - very similar to the -preempt kernel and based on the -generic kernel source tree, but uses a more aggressive
configuration to further reduce latency. Also known as a soft
-realtime kernel - is based on the vanilla kernel source tree with Ingo Molnar maintained PREEMPT_RT patch applied to it. Also known as a
hard real-time kernel.
Some confusion persists about the purposes of -lowlatency and
The goal of -realtime and -rt (hard real-time) kernels is to achieve
the lowest possible latency at every cost. In technical slang "hard
realtime systems should always meet their deadlines". Thus developers
should use the most advanced programming techniques (sleeping
spinlocks, PI Mutex, Full preemption, IRQ Threads and others) and
sacrifice things like reliability, power-saving and throughput. Almost
all parts of kernel should be analysed to guarantee that right
behaviour always occurs.
The goal of -preempt and -lowlatency (soft real-time) kernels is to
achieve good realtime characteristics, meanwhile offering welcomed
features like rock-solid reliability, good power-saving features and
also good throughput. But in this way it can't guarantee lowest
latency under all conditions.
I listed MAAS as I'm sure will be 3 of the 5 you were offered, I don't recall what the 5 options you mentioned were, but the other reference covers low latency
I'll provide links for HWE or Hardware Enablement Stack. Using HWE gets you the latest kernel (with more features & kernel modules [drivers]) useful for the latest hardware but not without the [tiny?] loss of stability (primarily they are tested less , esp. in production)
In the end it's your choice (you know your hardware, end-use, etc best); but for I'd guess 90+% of us it's the generic kernel.