Most modern (non budget) laptops will have dual mimo capability as Griffin has said. However you could go for triple ! I am Macbook's only and mine are all dual mimo (and have been for many years) but the new Macbook Pro has gone "triple" - I do appreciate that the MBP would be well over your budget - and arguably underpowered for some applications.
"One component that Apple hasn’t skimped on for this generation is the internal Wi-Fi. Rather than stick with the usual 802.11AC with a 2×2 MIMO antenna setup typically seen on most laptops, Apple has decided to opt for a 802.11AC with a 3×3 MIMO antenna setup which makes it one of the very few laptops on the market with a 3×3 MIMO antenna system."
I never said most laptops are MIMO capable, but quite a few. It is definetly worth checking before you buy. The MACs do have 3x3 MIMO but at the end of the day it is still a MAC.
Just browse the tech specs of the laptop, if the wireless specs say 802.11 a\b\g\n\ac then it is more than likely a single stream adapter. You are looking for MIMO or 2x2 or 3x3 or you might come across a 4x4 which is very rare in laptops.
An example below I have highlighted the LAN adapter in red as it is crucial you get a gigabit LAN adapter as well.
Realtek RTL8111HSH-CG 10/100/1000 GbE NIC
Intel® Dual Band Wireless-AC 9560 802.11a/b/g/n/ac (2x2) Wi-Fi® and Bluetooth® 5 Combo, non-vPro™
2 USB 3.1 Gen 1 1 USB 3.1 Type-C™ Gen 1 (Power delivery, DisplayPort™) 1 USB 2.0 (power port)