One powerful and quality service for integrated seo may not be inexpensive a priori. But you can always choose the most optimal in terms of quality and price.
For keyword research I recommend to try:
https://k-meta.com/ - offers a free subscription, and its cheapest subscription plan starts at $ 9.
Its advantages that attract me:
1) SERP in keyword overview
2) Phrase match for 31 countries and my favorite SE Suggestion
.
3) Domain analysis, which shows for what keywords the domain is in the top search results of Google.