Looking to buy a synth but I want the sequencer to be part of the synth. I want something that offers lots of possibilities with the sequencer and is fun rather than a chore.
I have owned the Monologue. Found the sequencer great to use. Haven’t tried out the A4, Minibrute 2s, or Digitone ( I did owne the Digitakt for a while).
A4 and DN sequencers are pretty close from DT.
On A4 you can direct jump, whereas on DN you can do polyrhythms.
Analog that can venture into FM territories, vs. FM synth that can venture into analog territories.
Pretty sure you can have different track length on the A4 as well. No tempo multiplier per track, though.
I recently bought a polyend medusa and it definitely has an interesting sequencer
From all my synths the Elektron boxes have the most deep sequencers built in. Many of the elder instruments have one melodic track and maybe an additional for modulation. Newer ones have a couple more, but the Elektrons have dozends to a hundred and the p-locking/sound-locking is unmatched.
To go crazy with an on-board step sequencer I would always recommend to check out one of the Elektrons 
You’re right.
From all the synths you listed, I only own the digitone. It can go really crazy if you want it to. It is also really fun to use. As with all the other elektron gear, the sequencer is very deep and allows for all kinds of crazy things on a per step basis.
Do you want to manually switch pattern? Or do you need a songmode?
What sounds should your new synth deliver? Whats missing here?
I’d choose a synth which is multitimbral and can be configured as poly synths too.
Digitone/A4.
You can use them as Monosynths or Poly. With Digitone you can sequence external gear via midi, with a4 not so easy, it’s more for connecting via good old voltage.
I’m not familiar with any of the other sequencers but I can tell you for a fact that you can go absolutely bonkers with the digitone sequencer. I personally like to take one track and design a sound that with p-locking can morph to create an entire drum kit of unique sounds.
The only downside to the digitone sequencer is this: you can’t p-lock arp settings but there is a workaround although a tad annoying but if you need to do it you can. And then also you can’t p-lock two separate sounds from the sound pool on the same step but I mean that makes sense.
As everyone else has said, what makes the electron boxes so dope is their sequencers. Digitone can go into some crazy territories sequencer wise and add FM synthesis on top of it then the range of sounds you can create are vast. Not gonna be as buttery as you’d be able to get on the A4 but you can definitely get warm and smooth pads as well as cold metallic percussive hits.
of the mentioned DN
A4 has parameter glide 
I think all in all the A4 is the one to get if you want the sequencer to be a big part of the synthesis/sound design. DN is almost as capable too, but trades the parameter glides for individual track scaling, and the synthesis is perhaps not as deep as on the A4 (but then again is FM)
Agreed.
Was working with Maschine sequencer before.
That is before getting a DT.
I don’t know your style of music and what sound you like. But If i had money, I will choose A4 from your list.
I really don’t like FM sound so DN is not for me. I owned a Minibrute 1 in the past and I found the sound a bit boring. Yes it’s analog, but I didn’t found any excitement to use it and have better warm and result with a Nord Lead 2x digital.
Never tried the Monologue but It look like very good sounding too. I think the A4 beat him for crazy things thanks to it’s sequencer with PLock.